For example, in a wireless communication network using an Internet protocol (IP) group (hereinafter arbitrarily abbreviated as “wireless IP network”), so-called mobile IP is defined in order to improve mobility of wireless communication apparatus (e.g. non-patent literature 1).
The mobile IP uses a care-of IP address (Care of Address) that is dynamically allocated according to the location of wireless communication apparatus. Non-patent literature 1: C. Perkins, “IP Mobility Support (RFC2002)”, [online], October 1996, IETF, [searched on Mar. 15, 2006], Internet <URL: http://www.ietf.org/rfc/rfc/2002.txt>.